Cell biology: Scientists fill in a piece of the copper transport puzzle

Humans acquire copper in trace amounts from food. Despite its low levels, copper is essential for the functioning of numerous important enzymes, for example some of those involved in synthesizing collagen and neurotransmitters. Notably, copper is required for building cytochrome c oxidase, known as COX, a large protein complex in mitochondria that forms the last step of the electron transport chain, which harvests energy for the production of ATP, the energy currency of the cell.

Paul Cobine of Auburn University and his collaborator Scot Leary at the University of Saskatchewan have been working for more than 10 years on understanding how copper is used to assemble COX. One of the basic questions was: How does copper get across the membranes in mitochondria?

Copper - Address - Cell - Proteins - Targets

"To get (copper) to the correct address (in the cell) without interfering with other proteins, or disrupting other targets that have a high chance of binding copper, is a herculean delivery effort," Cobine said. "This is akin to finding your way to an exit in a crowded bar without touching the other people or getting redirected. Then after finding the exit you must make sure you go through the right door."

In the new paper, the researchers used multiple lines of evidence to arrive at an answer: Copper is transported within mitochondria by a protein called SLC25A3. This discovery was...